Global warming and agriculture are cutting insects in half

image: Butterfly in Malaysia
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Credit: Dr Tim Newbold, UCL

Climate change and the intensive use of agricultural land have already been responsible for a 49% reduction in the number of insects in the worst affected regions of the world, according to a new study led by researchers from UCL.

The study published in Nature is the first to identify that an interaction between rising temperatures and changes in land use leads to widespread losses in many insect groups around the world.

Lead author Dr Charlie Outhwaite (UCL Center for Biodiversity & Environment Research, UCL Biosciences) said: “Many insects appear to be highly vulnerable to human pressures, which is concerning as climate change worsens and agricultural areas continue to expand. Our findings underscore the urgency of action to preserve natural habitats, slow the expansion of high-intensity agriculture, and reduce emissions to mitigate climate change.

“The loss of insect populations could be harmful not only to the natural environment, where insects often play a key role in local ecosystems, but it could also harm human health and food security, especially with loss of pollinators.

“Our findings may only represent the tip of the iceberg as there is limited evidence in some regions, particularly in the tropics, which we believe show quite high reductions in insect biodiversity in the worst areas. most affected.”

The researchers analyzed a large dataset of insect abundance and species richness from regions around the world, including three-quarters of a million records for almost 20,000 insect species.

The team compared insect biodiversity in different areas based on the intensity of agriculture in the region, as well as the region’s historical global warming.

They found that in areas with high agricultural intensity and substantial global warming, the number of insects was 49% lower than in most natural habitats with no recorded global warming, while the number of different species was lower. by 29%. Tropical areas have experienced the greatest declines in insect biodiversity linked to land use and climate change.

The researchers found that in areas of low-intensity agriculture and substantial global warming, having natural habitat nearby cushioned losses: where 75% of the land was covered in natural habitat, the insect abundance decreased by only 7%, compared to a reduction of 63%. in comparable areas with only 25% natural habitat coverage. Many insects depend on plants for shade on hot days, so a loss of natural habitats could make them more vulnerable to global warming.

The researchers say the decline in insects due to human influences could be even greater than their findings suggest, as many areas with long histories of human impacts may have already suffered biodiversity losses before the start of the climate change period. study, nor did the study take into account the effects of other factors such as pollution.

Lead author Dr Tim Newbold (UCL Center for Biodiversity and Environment Research) said: “The environmental damage of high-intensity farming presents a tricky challenge as we try to address the food needs of a growing population. We previously found that pollinating insects are particularly vulnerable to agricultural expansion, as they appear to be more than 70% less abundant in high-intensity croplands than in wild sites. Careful management of agricultural areas, such as preserving natural habitats near farmland, can help ensure vital insects can still thrive.

Joint first author Peter McCann, who conducted the research while completing an MSc at UCL’s Center for Biodiversity and Environment Research, said: “We need to recognize how important insects are to the environment as a whole, as well as for human health and well-being, in order to address the threats we pose to them before many species are lost forever.

Scientists at UCL’s Center for Biodiversity and Environment Research are at the forefront of research into human impacts on the planet, for example developing the science that underpins the United Nations Red List. IUCN that quantifies the risk of extinction, and finding that changes in land use can increase the risks of epidemics like Covid-19 jumping from animals to humans. The center’s new interdisciplinary People and Nature Lab is developing innovative approaches, such as citizen science programs and the use of artificial intelligence, to address these pressing global challenges and foster a more sustainable relationship between people and nature. .

The research was supported by the Natural Environment Research Council and the Royal Society.

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